Vapor streams containing volatile and semi-volatile organic compounds (VOCs and SVOCs) are produced by industrial processes; as a result of the transfer of liquids from one containment body to another due to the displacement of air or liquid, by their volatilization during the industrial process or by contaminated soil remediation or other environmental cleanup operations. These processes typically use either vacuum or pressure pumps, blowers or compressors. Air displaced in the process becomes saturated with vapors containing VOCs and SVOCs that can cause environmental damage or health issues.
Until most recently, control and destruction of these vapors was traditionally done with different pollution control devices that controlled and/or oxidized the vapors. Suitable devices have included open burning flares, thermal oxidizers, catalytic oxidizers and conventional internal combustion engines (ICE). A conventional ICE is one that utilizes a standard carburetor which has one fuel input and one air input. Recently implemented environmental regulations or changes to existing regulations have made the present form of oxidizers either too polluting, unsafe to operate, too expensive or obsolete. Alternatively, VOCs and SVOCs can be removed and controlled by adsorption onto activated carbon, but excessive cost and handling are of concern due to the large volumes of carbon typically required for proper abatement.
Industrial process vapor streams vary in volume/density and BTU content of VOCs and SVOCs which directly impacts the composition of the air fuel mixture going to an oxidation vehicle. While carbon adsorption is not adversely affected by a change in air fuel mixture, safety and control limitations for current oxidation technologies such as flares, thermal/catalytic oxidizers and conventional ICE's can require significant and expensive amounts of alternate fuel source in order to combust the VOCs and SVOCs in the vapor stream. In addition, traditional oxidizers are usually physically large in size and are oversized in order to handle fluctuation of the BTU content of the vapor stream. As a result, traditional oxidizers burn excessive amounts of alternate fuel, and therefore generate significant amount of greenhouse gas emissions without effectively recovering the energy available from the VOCs and SVOCs in the vapor stream.
Similarly, the adsorption of organic compounds onto an activated carbon process bed requires a large footprint storage container. A large volume of charcoal is required in order to process VOCs in a comparable amount of time as that of other oxidizing vehicles. Additionally, once the activated carbon has reached its maximum “spent” loading capacity it has to be replaced by a new container of charcoal. The spent charcoal has to be desorbed to reprocess/recover it for reuse. This reprocessing requires energy (alternate fuel source), generates additional waste streams and produces greenhouse gas emissions. Furthermore, carbon is unsafe for processing high VOC content vapor streams because the carbon may easily ignite.
A conventional ICE attempts to use the volatile vapor stream as the primary fuel source. However, it does not have the capability to handle the rapidly changing air flow volume/density and varying BTU concentrations found in the process vapor stream. As it uses large amounts of an alternate fuel source (typically propane) mixed with the process vapor stream in order to operate correctly, a conventional ICE is inefficient in reduction of the vapor stream of VOCs/SVOCs and generates more secondary pollutants such as NOx and CO when compared to the present invention, which utilizes a unique control/mixing system with multiple fuel/air valves, specialized software and a custom air fuel ratio controller.